cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-5 of 5 results.

A297323 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1 - j*x^j)^k.

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -2, -2, 0, 1, -3, -3, -1, 0, 1, -4, -3, 2, -1, 0, 1, -5, -2, 8, 4, 5, 0, 1, -6, 0, 16, 9, 16, 1, 0, 1, -7, 3, 25, 9, 18, -3, 13, 0, 1, -8, 7, 34, 0, 4, -35, 6, 4, 0, 1, -9, 12, 42, -21, -26, -90, -33, -31, 0, 0, 1, -10, 18, 48, -56, -66, -145, -56, -66, -72, 2, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 28 2017

Keywords

Examples

			G.f. of column k: A_k(x) = 1 - k*x + (1/2)*k*(k - 5)*x^2 - (1/6)*k*(k^2 - 15*k + 20)*x^3 + (1/24)*k*(k^3 - 30*k^2 + 155*k - 150)*x^4 - (1/120)*k*(k^4 - 50*k^3 + 575*k^2 - 1750*k + 624)*x^5 + ...
Square array begins:
  1,  1,   1,   1,   1,   1,  ...
  0, -1,  -2,  -3,  -4,  -5,  ...
  0, -2,  -3,  -3,  -2,   0,  ...
  0, -1,   2,   8,  16,  25,  ...
  0, -1,   4,   9,   9,   0,  ...
  0,  5,  16,  18,   4, -26,  ...
		

Crossrefs

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[Product[(1 - i x^i)^k, {i, 1, n}], {x, 0, n}]][j - n], {j, 0, 11}, {n, 0, j}] // Flatten
  • PARI
    first(n, k) = my(res = matrix(n, k)); for(u=1, k, my(col = Vec(prod(j=1, n, (1 - j*x^j)^(u-1)) + O(x^n))); for(v=1, n, res[v, u] = col[v])); res \\ Iain Fox, Dec 28 2017

Formula

G.f. of column k: Product_{j>=1} (1 - j*x^j)^k.

A297322 a(n) = [x^n] Product_{k>=1} (1 + k*x^k)^n.

Original entry on oeis.org

1, 1, 5, 28, 137, 726, 3896, 21071, 115089, 633007, 3500740, 19448573, 108458924, 606787572, 3404112479, 19142919543, 107874784017, 609021410570, 3443952349385, 19503777943838, 110599636109572, 627924447630011, 3568885868192419, 20304321490356084
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 28 2017

Keywords

Crossrefs

Main diagonal of A297321.

Programs

  • Maple
    f:= proc(n) local k;
    coeff(series(mul((1+k*x^k)^n,k=1..n),x,n+1),x,n);
    end proc:
    map(f, [$0..30]); # Robert Israel, Dec 28 2017
  • Mathematica
    Table[SeriesCoefficient[Product[(1 + k x^k)^n, {k, 1, n}], {x, 0, n}], {n, 0, 24}]

Formula

a(n) = A297321(n,n).
a(n) ~ c * d^n / sqrt(n), where d = 5.814548482877687529318372516965305077397562... and c = 0.2563102401728134539247148322678842806264... - Vaclav Kotesovec, Aug 01 2019

A297329 a(n) = [x^n] Product_{k>=1} 1/(1 - k*x^k)^n.

Original entry on oeis.org

1, 1, 7, 37, 219, 1276, 7687, 46551, 285043, 1756243, 10883842, 67751289, 423366831, 2654041235, 16683909711, 105129718102, 663837626163, 4199521413019, 26610335585263, 168864540960165, 1073001606214814, 6826237566223329, 43474472693256491, 277152041235941803
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 28 2017

Keywords

Crossrefs

Main diagonal of A297328.

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - k x^k)^n, {k, 1, n}], {x, 0, n}], {n, 0, 23}]

Formula

a(n) = A297328(n,n).
a(n) ~ c * d^n / sqrt(n), where d = 6.51548390811914394587815688142024783108478... and c = 0.2552310487728179222346375591994440863074... - Vaclav Kotesovec, Aug 01 2019

A297326 a(n) = [x^n] Product_{k>=1} 1/(1 + k*x^k)^n.

Original entry on oeis.org

1, -1, -1, -1, 27, -76, 95, -295, 2035, -8119, 22714, -66793, 254223, -988651, 3444055, -11402626, 39248691, -141740051, 511583207, -1798826901, 6256648862, -22054706773, 78889160635, -281698897727, 996551999479, -3520566280801, 12522382445455, -44731559517301
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 28 2017

Keywords

Crossrefs

Main diagonal of A297325.

Programs

  • Maple
    f:= proc(n) local k;
    coeff(series(mul(1/(1+k*x^k)^n,k=1..n),x,n+1),x,n);
    end proc:
    map(f, [$0..30]); # Robert Israel, Dec 28 2017
  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 + k x^k)^n, {k, 1, n}], {x, 0, n}], {n, 0, 27}]

Formula

a(n) = A297325(n,n).

A298986 a(n) = [x^n] Product_{k>=1} (1 - n*x^k)^k.

Original entry on oeis.org

1, -1, -4, 9, 48, 100, -756, -3479, -1600, 24462, 225900, 364573, -643536, -9251736, -36989316, -32397975, 165039872, 1725828525, 5338814652, 8082713829, -26321848400, -233434232766, -811526778964, -1731126953532, 1151302859712, 23632432765000, 113461901639788, 287935019845749
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 31 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[(1 - n x^k)^k, {k, 1, n}], {x, 0, n}], {n, 0, 27}]
Showing 1-5 of 5 results.